package com.java;

import java.util.concurrent.ExecutionException;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;

/**
 * @author jingjintao
 * @date 2021/10/27 - 23:52
 **/
public class ForkJoinDemo {

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        MyTask myTask = new MyTask(0, 10);
        ForkJoinPool forkJoinPool = new ForkJoinPool();

        ForkJoinTask<Integer> forkJoinTask = forkJoinPool.submit(myTask);
        System.out.println(forkJoinTask.get());

        forkJoinPool.shutdown();
    }
}

class MyTask extends RecursiveTask<Integer> {

    private static final Integer ADJUST_VALUE = 10;
    private int begin;
    private int end;
    private int result;

    public MyTask(int begin, int end) {
        this.begin = begin;
        this.end = end;
    }

    @Override
    protected Integer compute() {
        if((end - begin) <= ADJUST_VALUE){
            for (int i = begin; i <=  end; i++) {
                result += i;
            }
        }else {
            int middle = (begin+end)/2;
            MyTask myTask1 = new MyTask(begin, middle);
            MyTask myTask2 = new MyTask(middle+1, end);
            myTask1.fork();
            myTask2.fork();

            result = myTask1.join() + myTask2.join();
        }
        return result;
    }
}
